Body fluids may need to be withdrawn from a patient in the course of medical treatment. Two common medical procedures requiring fluid removal are thoracentesis and paracentesis.
In paracentesis, peritoneal fluid is aspirated from the abdomen. Typical patients have tense ascites resulting from liver disease and portal hypertension, which may cause discomfort, respiratory distress, and the formation and rupture of umbilical hernias. Paracentesis has been observed to provide quick and effective relief with few adverse side effects. Other treatment options, such as the use of diuretics, are available, but may not provide as effective relief as paracentesis. Additionally, many patients with ascites have renal impairment and cannot use the high doses of diuretics necessary to effectively treat the ascites. See “Large-Volume Paracentesis in Nonedematous Patients with Tense-Ascites: Its Effect on Intravascular Volume,” Pinto et al., Hepatology, Vol. 8, No. 2, pp. 207–210, 1988. Relatively large volumes of fluid, such as five liters, may be withdrawn from a patient during one paracentesis procedure.
Many existing devices are capable of performing paracentesis. At its simplest, a paracentesis device need only include a hollow needle with one end inserted into the patient and the other end attached to a negative pressure device, such as a syringe or vacuum bottle. However, more specialized devices have been developed to allow safer, more comfortable, and more sanitary paracentesis. These devices may allow for body fluid to be dispensed into at least two containers, so that one container may be filled with fluid for diagnostic purposes and the other container may be filled with waste fluid. Another development has been the use of Kuss or Verres type needle assemblies, where a blunt drainage needle is attached to a retractile sharp introducer needle. This reduces the likelihood of the sharp needle damaging internal tissue during paracentesis. A further development is to drain body fluid through a blunt-tipped catheter introduced by a sharp introducing needle, which allows the sharp needle to be removed from the patient after a relatively quick introduction process and avoids the prolonged presence of a sharp needle in the body of the patient.
Problems may arise when drainage is diverted from one container to another if the drainage system is not airtight. Air could contaminate a sample or enter the body of the patient and cause injury. Known devices that are meant to be airtight have tubes and multiple containers attached to the devices which make the devices cumbersome and somewhat difficult to insert into the patient. Also, known devices require manipulation of a manual valve, such as a stopcock to work effectively. If the stopcock is not set at the proper setting, the device may admit air into the patient or otherwise malfunction. Problems also may arise in devices which allow a needle assembly to be withdrawn. Air must be prevented from entering the patient when the fluid is withdrawn. Also, body fluid must be prevented from leaking out of the device through the space formerly occupied by the needle assembly.
Thoracentesis is a procedure similar to paracentesis, except that effusion fluid is withdrawn from the pleural region instead of the abdomen. Normally, the pleural space contains approximately 5 to 20 ml of fluid. The fluid is the result of the hydrostatic-onctotic pressure of the capillaries of the parietal pleura. The turnover of the fluid in the pleural space is normally quite rapid, so that 5 to 10 liters of fluid move through the pleural space each day. A disruption in the balance between the movement of fluid into the pleural space and the movement of fluid out of the pleural space may produce excessive fluid accumulation in the pleural space. Pleural effusion is particularly common in patients with disseminated breast cancer, lung cancer or lymphatic cancer and patients with congestive heart failure, but also occurs in patients with many other forms of malignancy.
Pleural effusion may cause dyspnea, coughing, and chest pain, which diminish a patient's quality of life. Although pleural effusion typically occurs toward the end of terminal malignancies, such as breast cancer, it occurs earlier in other diseases. Therefore, relieving the clinical manifestations of pleural effusion is for real and extended advantage to the patient. For example, non-breast cancer patients with pleural effusion have been known to survive for years. See “Pleural Effusion in Cancer Patients,” Izbicki et al., Cancer, October 1975, p. 1511.
There are several treatments for pleural effusion. If the patient is asymptomatic and the effusion is known to be malignant or paramalignant, no treatment may be required. Pleurectomy and pleural abrasion are generally effective in obliterating the pleural space, thus controlling the malignant pleural effusion. However, pleurectomy is a major surgical procedure associated with substantial morbidity and some mortality. Chemotherapy is generally disappointing; however, it may produce good responses for patients with lymphoma, breast cancer, or small-cell carcinoma. Another approach is to surgically implant a chest tube. However, such a tube is painful to the patient, both when it is inserted and during the time that it remains in the pleural space. Improvements on the traditional chest tube are described in U.S. Pat. No. 5,484,401, commonly owned with the present application.
Despite other treatment options, thoracentesis remains the most common approach to removing pleural fluid. However, thoracentesis poses the danger of causing pneumothorax, a collapsed lung. Pneumothorax can be caused directly by puncturing a lung with a needle assembly or catheter tip or indirectly by allowing air to enter the pleural space. Normally, the pleural space is at negative pressure relative to the atmosphere, which helps keep the lungs expanded. If the atmosphere is allowed to communicate with the pleural space, the pleural space may no longer be at negative pressure and pneumothorax may result.
Thoracentesis devices have been developed to reduce the risk of pneumothorax and other similar problems that may result from the procedure. In general, these devices incorporate similar protections as do paracentesis devices. For example, U.S. Pat. No. 4,447,235 by Clark discloses a thoracentesis device with a catheter introduced by a removable needle assembly, with a valve that closes upon removal of the needle assembly. The purpose of the valve is to prevent air from entering the body of the patient. U.S. Pat. Nos. 4,784,156, 4,832,044, 4,840,184, and 4,844,087 by Garg disclose similar devices with a manual valve that may be closed after withdrawal of the needle assembly. However, none of the previous devices allow for a truly fail-safe operation, as various valves must be properly set by the operator when changing from one drain port to another or when withdrawing the introducing needle assembly from the patient. Also, care must be taken to avoid accidental withdrawal of the introducing needle assembly, as in the disclosed devices where the needle assembly is not firmly attached to the remainder of the device. Further, the disclosed valves that allow for catheter drainage after removal of an introducing needle assembly rely on a single contact point. Due to the possibly dire consequences of a valve failure, such valves may not produce acceptably safe thoracentesis.
A Verres-type needle assembly that may be used for thoracentesis is disclosed in U.S. Pat. No. 5,334,159 by Turkel. While this reduces the risk of pneumothorax due to lung puncture, the Turkel device does not improve the safety of thoracentesis when the introducing needle assembly is withdrawn or solve the problems associated with multiple drainage ports. Thus there is a need for a safer and more reliable device that may be used for paracentesis and thoracentesis. Another device is described in U.S. Pat. No. 5,725,906, issued Mar. 10, 1998.
Other difficulties with existing systems relate to manufacturing, storing and using the vacuum element. Syringes are sometimes used to generate the vacuum, but syringes are somewhat complicated to manufacture and use. An alternative vacuum source is a vacuum bottle. In that approach, a vacuum is created in an air-tight bottle at the manufacturing stage, and then the bottle is sealed. The bottle is then tapped at the time of use so that the vacuum can be applied to a drainage line to remove the undesired body fluids.
This is quite ingenious in concept but somewhat difficult to implement. There is always some risk that the vacuum will be lost in transit before use, either by leaks, fractures or just air permeating through a plastic wall. Moreover, the loss of vacuum is not necessarily apparent to the user; a bottle with a perfect vacuum inside looks no different than a bottle of air. Another problems is in tapping the bottle. This requires a system that pierces a vacuum seal but does not allow air to enter the bottle, except through the draw line. Such a system should be easy to operate but not susceptible to accidental operation.
The contents of each document referred to herein is hereby incorporated by reference, although it is noted that such documents are not admitted to be prior art and are only referenced as they may be helpful to an understanding and appreciation of the present invention.